1. Don't try to do too much with a single mouse click. This one’s important, as it’s probably the biggest difference between amateur retoucher and professional. Set the opacity to any amount less than 100 percent opacity, say 25 or 50 percent, and work the same spot over and over. This technique allows you to slowly build up pixel density without creating hard edges. It’s especially helpful when cloning over subtle gradations—like those often found in skies or studio backgrounds. This approach does fall apart sometimes, like when you have a lot of texture or pattern to deal with. In these cases alignment is key.
3. Utilize additional cloning modes such as color, luminosity and saturation. While the normal mode duplicates pixel A directly to pixel B, these additional stamping modes can duplicate only part of the pixel to its counterpart. That might be the color of a pixel, or the saturation (without changing the color) or even the brightness (without changing, contrast, color or the pattern of the pixels). I find these options extremely helpful for smoothing out skin tones and crafting better portraits, but they apply to a number of scenarios.
5. While most of my stamping is done with round brushes, expert retouchers tout the benefits of specialized brush shapes. Brushes shaped like foliage, for example, can make blending leaves and flowers more natural. Square edges brushes might work better when you’re not blending organic shapes, just like random scattered brushes can help randomize natural patterns just as Mother Nature would. Whatever the subject there’s a custom brush to fit it. You’ve just got to look beyond the basics.